Russell Brand joins anti-capitalist protesters during the Million Masks March in London
Photograph: Jack Taylor/AFP/Getty Images

A group of more than 50 Hollywood stars, fashion designers, musicians, writers and philosophers have joined forces to call for greater legal protection and support for whistleblowers around the world.

The diverse alliance includes philosophers Slavoj Žižek and Noam Chomsky, movie A-listers Susan Sarandon and Peter Sarsgaard, artist Sarah Lucas, and musicians Moby and MIA – not to mention the ubiquitous Russell Brand. They have come together to fly the flag for the unsung whistleblower and, in a joint statement, say that those sources and publishers who “risks their lives and careers to stand up for truth and justice” should be worthy of society’s protection and support.

Edward Snowden. Photograph: Reuters

The signatories mention four individuals by name: Edward Snowden, the former National Security Agency contractor now in exile in Russia; Chelsea Manning, serving 35 years in military custody as the source of the massive 2010 WikiLeaks trove of US state secrets; Daniel Ellsberg, of the 1970s Pentagon Papers; and Jeremy Hammond, who is on a 10-year sentence for his part in Anonymous’s release of emails from the intelligence firm Stratfor.

Thanks to their courage, the statement says, “the public can finally see for themselves the war crimes, corruption, mass surveillance and abuses of power of the US government and other governments around the world.”

The participants also name-check WikiLeaks, which they say is “essential for its fearless dedication in defending these sources and publishing their truths”. Its founder, Julian Assange, remains in asylum in the Ecuadorean embassy in London following allegations of sexual assault raised in Sweden.

The statement was organized by the Courage Foundation, the body recently set up by Sarah Harrison of WikiLeaks which is acting as the legal defense fund for Snowden. It has been timed to coincide with the release of Laura Poitras’s documentary about Snowden, CitizenFour.

“I didn’t ask Edward Snowden to stick his neck out for me,” said one of the signatories, Vivienne Westwood. “But now that he did I ask myself where would we be without him?”

MIA. Photograph: D Kambouris/Getty

It also comes at a moment where the US government is perceived to be taking a particularly aggressive approach to official leakers. Including Snowden and Manning, there have been a total of eight prosecutions by the Obama administration relating to leaks under the 1917 Espionage Act – more than those that were brought by all previous presidents combined.

Prosecutors are also continuing to threaten with subpoena the New York Times reporter James Risen in connection with the upcoming trial of one of the eight, a former CIA operative Jeffrey Sterling.

The list of those who have backed the whistleblower statement also includes movie directors Alfonso Cuarón, Terry Gilliam and Ken Loach; musicians Robbie Charter of the Avalanches, PJ Harvey and Thurston Moore of Sonic Youth; and writers Roddy Doyle and Hanif Kureishi.